Radial Transport of Ions in Roots 1

AUTOR(ES)

Yu, Grace Hu

RESUMO

Measurements were made of the relative amounts of 86Rb, 36Cl, and 32P accumulated in the cortex and stele of intact roots of corn (Zea mays), either detached or attached to their shoots. Both 4- and 7-day-old roots accumulated as much or more 86Rb in the stele as in the cortex. In experiments with 36Cl, cortex and stele accumulated the same amount, except for 4-day-old and 7-day-old attached roots, in which the cortex contained more 36Cl than the stele after 23 hr. An additional study of 32P uptake showed greater accumulation in the cortex than the stele for a short period of time, but as much in the stele as in the cortex after 8 to 24 hr. Transport of 86Rb, 36Cl, and 32P into the xylem exudate increased with increasing accumulation of these ions in stele and cortex of the root. These experiments show no consistent difference between cortex and stele of intact corn roots with respect to their ability to accumulate several kinds of ions.

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